Developing low-cost tandem perovskite solar cells

Research is underway at the University of Toledo to create a high-efficiency, low-cost material that can harness solar energy.

Working in collaboration with the US Department of Energy’s National Renewable Energy Lab, University of Toledo Professor of Physics Dr Yanfa Yan has reported a significant breakthrough in the chemical formula and process to make the new material, known as tandem perovskite solar cells.

The research, published in the journal Science, outlines how the photovoltaics team is fine-tuning a mix of lead and tin to advance the technology closer to its maximum efficiency. Efforts have so far brought the efficiency of the new solar cell to about 23% compared with silicon solar panels on the market today, which have an efficiency rating of around 18%.

Using a chemical compound called guanidinium thiocyanate, the research team has improved the structural and optoelectronic properties of the lead–tin-mixed perovskite films.

Dr Yan’s team identified the ideal properties of perovskites about five years ago. He has since focused on producing an all-perovskite tandem solar cell that brings together two different solar cells to increase the total electrical power generated by using two different parts of the sun’s spectrum.

“We are producing higher-efficiency, lower-cost solar cells that show great promise to help solve the world energy crisis,” Dr Yan said.

“The meaningful work will help protect our planet for our children and future generations. We have a problem consuming most of the fossil energies right now, and our collaborative team is focused on refining our innovative way to clean up the mess,” he continued.

“Our … research is ongoing to make cheaper and more efficient solar cells that could rival and even outperform the prevailing silicon photovoltaic technology,” said Dr Zhaoning Song, study co-author and Research Assistant Professor at The University of Toledo Department of Physics and Astronomy.

“Our tandem solar cells, with two layers of perovskites, deliver high-power conversion efficiency and have the potential to bring down production costs of solar panels, which is an important advance in photovoltaics,” he added.

While Dr Yan’s team has improved the quality of the materials and the process to manufacture them at a low cost, more progress needs to be made.

“The material cost is low and the fabrication cost is low, but the lifetime of the material is still an unknown,” Song said. “We need to continue to increase efficiency and stability.”

The research team also wants to work with the solar industry to ensure that solar panels made from the new material can be recycled so they don’t have a negative impact on the environment.

Dr Yan envisions the technology will be ready to debut in full-sized solar panels in the consumer market in the near future. Currently, silicon is the solar-cell material of choice for converting the sunlight into electrical energy, but perovskites are considered the future of solar cells, as their easily synthesised distinctive structure makes them perfect for enabling low-cost, efficient photovoltaics.

Image caption: Dr Zhaoning Song holds a perovskite solar cell mini-module he developed with Dr Yanfa Yan. Image credit: Daniel Miller, University of Toledo.